//-----------------------------------------------------------------------------
// Copyright (C) 2018 Merlok
// Copyright (C) 2018 drHatson
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// crypto commands
//-----------------------------------------------------------------------------

#include "crypto/libpcrypto.h"
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <mbedtls/asn1.h>
#include <mbedtls/aes.h>
#include <mbedtls/cmac.h>
#include <mbedtls/pk.h>
#include <mbedtls/ecdsa.h>
#include <mbedtls/sha256.h>
#include <mbedtls/sha512.h>
#include <mbedtls/ctr_drbg.h>
#include <mbedtls/entropy.h>
#include <mbedtls/error.h>
#include <crypto/asn1utils.h>
#include <util.h>


// NIST Special Publication 800-38A — Recommendation for block cipher modes of operation: methods and techniques, 2001.
int aes_encode(uint8_t *iv, uint8_t *key, uint8_t *input, uint8_t *output, int length){
	uint8_t iiv[16] = {0};
	if (iv)
		memcpy(iiv, iv, 16);

	mbedtls_aes_context aes;
	mbedtls_aes_init(&aes);
	if (mbedtls_aes_setkey_enc(&aes, key, 128))
		return 1;
	if (mbedtls_aes_crypt_cbc(&aes, MBEDTLS_AES_ENCRYPT, length, iiv, input, output))
		return 2;
	mbedtls_aes_free(&aes);

	return 0;
}


int aes_decode(uint8_t *iv, uint8_t *key, uint8_t *input, uint8_t *output, int length){
	uint8_t iiv[16] = {0};
	if (iv)
		memcpy(iiv, iv, 16);

	mbedtls_aes_context aes;
	mbedtls_aes_init(&aes);
	if (mbedtls_aes_setkey_dec(&aes, key, 128))
		return 1;
	if (mbedtls_aes_crypt_cbc(&aes, MBEDTLS_AES_DECRYPT, length, iiv, input, output))
		return 2;
	mbedtls_aes_free(&aes);

	return 0;
}


// NIST Special Publication 800-38B — Recommendation for block cipher modes of operation: The CMAC mode for authentication.
// https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Standards-and-Guidelines/documents/examples/AES_CMAC.pdf
int aes_cmac(uint8_t *iv, uint8_t *key, uint8_t *input, uint8_t *mac, int length) {
	memset(mac, 0x00, 16);

	//  NIST 800-38B
	return mbedtls_aes_cmac_prf_128(key, MBEDTLS_AES_BLOCK_SIZE, input, length, mac);
}


int aes_cmac8(uint8_t *iv, uint8_t *key, uint8_t *input, uint8_t *mac, int length) {
	uint8_t cmac[16] = {0};
	memset(mac, 0x00, 8);

	int res = aes_cmac(iv, key, input, cmac, length);
	if (res)
		return res;

	for(int i = 0; i < 8; i++)
		mac[i] = cmac[i * 2 + 1];

	return 0;
}


static uint8_t fixed_rand_value[250] = {0};

static int fixed_rand(void *rng_state, unsigned char *output, size_t len) {
	if (len <= 250) {
		memcpy(output, fixed_rand_value, len);
	} else {
		memset(output, 0x00, len);
	}

	return 0;
}


int sha256hash(uint8_t *input, int length, uint8_t *hash) {
	if (!hash || !input)
		return 1;

	mbedtls_sha256_context sctx;
	mbedtls_sha256_init(&sctx);
	mbedtls_sha256_starts(&sctx, 0); // SHA-256, not 224
	mbedtls_sha256_update(&sctx, input, length);
	mbedtls_sha256_finish(&sctx, hash);
	mbedtls_sha256_free(&sctx);

	return 0;
}


int sha512hash(uint8_t *input, int length, uint8_t *hash) {
	if (!hash || !input)
		return 1;

	mbedtls_sha512_context sctx;
	mbedtls_sha512_init(&sctx);
	mbedtls_sha512_starts(&sctx, 0); //SHA-512, not 384
	mbedtls_sha512_update(&sctx, input, length);
	mbedtls_sha512_finish(&sctx, hash);
	mbedtls_sha512_free(&sctx);

	return 0;
}


int ecdsa_init_str(mbedtls_ecdsa_context *ctx, mbedtls_ecp_group_id curveID, char *key_d, char *key_x, char *key_y) {
	if (!ctx)
		return 1;

	int res;

	mbedtls_ecdsa_init(ctx);
	res = mbedtls_ecp_group_load(&ctx->grp, curveID);
	if (res)
		return res;

	if (key_d) {
		res = mbedtls_mpi_read_string(&ctx->d, 16, key_d);
		if (res)
			return res;
	}

	if (key_x && key_y) {
		res = mbedtls_ecp_point_read_string(&ctx->Q, 16, key_x, key_y);
		if (res)
			return res;
	}

	return 0;
}


int ecdsa_init(mbedtls_ecdsa_context *ctx, mbedtls_ecp_group_id curveID, uint8_t *key_d, uint8_t *key_xy) {
	if (!ctx)
		return 1;

	int res;

	mbedtls_ecdsa_init(ctx);
	res = mbedtls_ecp_group_load(&ctx->grp, curveID);
	if (res)
		return res;

	size_t keylen = (ctx->grp.nbits + 7 ) / 8;
	if (key_d) {
		res = mbedtls_mpi_read_binary(&ctx->d, key_d, keylen);
		if (res)
			return res;
	}

	if (key_xy) {
		res = mbedtls_ecp_point_read_binary(&ctx->grp, &ctx->Q, key_xy, keylen * 2 + 1);
		if (res)
			return res;
	}

	return 0;
}


int ecdsa_key_create(mbedtls_ecp_group_id curveID, uint8_t *key_d, uint8_t *key_xy) {
	int res;
	mbedtls_ecdsa_context ctx;
	ecdsa_init(&ctx, curveID, NULL, NULL);


	mbedtls_entropy_context entropy;
	mbedtls_ctr_drbg_context ctr_drbg;
	const char *pers = "ecdsaproxmark";

	mbedtls_entropy_init(&entropy);
	mbedtls_ctr_drbg_init(&ctr_drbg);

	res = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy, (const unsigned char *)pers, strlen(pers));
	if (res)
		goto exit;

	res = mbedtls_ecdsa_genkey(&ctx, curveID, mbedtls_ctr_drbg_random, &ctr_drbg);
	if (res)
		goto exit;

	size_t keylen = (ctx.grp.nbits + 7) / 8;
	res = mbedtls_mpi_write_binary(&ctx.d, key_d, keylen);
	if (res)
		goto exit;

	size_t public_keylen = 0;
	uint8_t public_key[200] = {0};
	res = mbedtls_ecp_point_write_binary(&ctx.grp, &ctx.Q, MBEDTLS_ECP_PF_UNCOMPRESSED, &public_keylen, public_key, sizeof(public_key));
	if (res)
		goto exit;

	if (public_keylen != 1 + 2 * keylen) { // 0x04 <key x><key y>
		res = 1;
		goto exit;
	}
	memcpy(key_xy, public_key, public_keylen);

exit:
	mbedtls_entropy_free(&entropy);
	mbedtls_ctr_drbg_free(&ctr_drbg);
	mbedtls_ecdsa_free(&ctx);
	return res;
}


char *ecdsa_get_error(int ret) {
	static char retstr[300];
	memset(retstr, 0x00, sizeof(retstr));
	mbedtls_strerror(ret, retstr, sizeof(retstr));
	return retstr;
}


int ecdsa_public_key_from_pk(mbedtls_pk_context *pk, mbedtls_ecp_group_id curveID, uint8_t *key, size_t keylen) {
	int res = 0;
	size_t realkeylen = 0;

	mbedtls_ecdsa_context ctx;
	mbedtls_ecdsa_init(&ctx);

	res = mbedtls_ecp_group_load(&ctx.grp, curveID);
	if (res)
		goto exit;

	size_t private_keylen = (ctx.grp.nbits + 7) / 8;
	if (keylen < 1 + 2 * private_keylen) {
		res = 1;
		goto exit;
	}

	res = mbedtls_ecdsa_from_keypair(&ctx, mbedtls_pk_ec(*pk) );
	if (res)
		goto exit;

	res = mbedtls_ecp_point_write_binary(&ctx.grp, &ctx.Q, MBEDTLS_ECP_PF_UNCOMPRESSED, &realkeylen, key, keylen);
	if (realkeylen != 1 + 2 * private_keylen)
		res = 2;
exit:
	mbedtls_ecdsa_free(&ctx);
	return res;
}


int ecdsa_signature_create(mbedtls_ecp_group_id curveID, uint8_t *key_d, uint8_t *key_xy, uint8_t *input, int length, uint8_t *signature, size_t *signaturelen, bool hash) {
	int res;
	*signaturelen = 0;

	uint8_t shahash[32] = {0};
	res = sha256hash(input, length, shahash);
	if (res)
		return res;

	mbedtls_entropy_context entropy;
	mbedtls_ctr_drbg_context ctr_drbg;
	const char *pers = "ecdsaproxmark";

	mbedtls_entropy_init(&entropy);
	mbedtls_ctr_drbg_init(&ctr_drbg);

	res = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy, (const unsigned char *)pers, strlen(pers));
	if (res)
		goto exit;

	mbedtls_ecdsa_context ctx;
	ecdsa_init(&ctx, curveID, key_d, key_xy);
	res = mbedtls_ecdsa_write_signature(&ctx, MBEDTLS_MD_SHA256, hash?shahash:input, hash?sizeof(shahash):length, signature, signaturelen, mbedtls_ctr_drbg_random, &ctr_drbg);

exit:
	mbedtls_ctr_drbg_free(&ctr_drbg);
	mbedtls_ecdsa_free(&ctx);
	return res;
}


int ecdsa_signature_create_test(mbedtls_ecp_group_id curveID, char *key_d, char *key_x, char *key_y, char *random, uint8_t *input, int length, uint8_t *signature, size_t *signaturelen) {
	int res;
	*signaturelen = 0;

	uint8_t shahash[32] = {0};
	res = sha256hash(input, length, shahash);
	if (res)
		return res;

	int rndlen = 0;
	param_gethex_to_eol(random, 0, fixed_rand_value, sizeof(fixed_rand_value), &rndlen);

	mbedtls_ecdsa_context ctx;
	ecdsa_init_str(&ctx, curveID, key_d, key_x, key_y);
	res = mbedtls_ecdsa_write_signature(&ctx, MBEDTLS_MD_SHA256, shahash, sizeof(shahash), signature, signaturelen, fixed_rand, NULL);

	mbedtls_ecdsa_free(&ctx);
	return res;
}


int ecdsa_signature_verify_keystr(mbedtls_ecp_group_id curveID, char *key_x, char *key_y, uint8_t *input, int length, uint8_t *signature, size_t signaturelen, bool hash) {
	int res;
	uint8_t shahash[32] = {0};
	res = sha256hash(input, length, shahash);
	if (res)
		return res;

	mbedtls_ecdsa_context ctx;
	ecdsa_init_str(&ctx, curveID, NULL, key_x, key_y);
	res = mbedtls_ecdsa_read_signature(&ctx, hash?shahash:input, hash?sizeof(shahash):length, signature, signaturelen);

	mbedtls_ecdsa_free(&ctx);
	return res;
}


int ecdsa_signature_verify(mbedtls_ecp_group_id curveID, uint8_t *key_xy, uint8_t *input, int length, uint8_t *signature, size_t signaturelen, bool hash) {
	int res;
	uint8_t shahash[32] = {0};
	if (hash) {
		res = sha256hash(input, length, shahash);
		if (res)
			return res;
	}

	mbedtls_ecdsa_context ctx;
	res = ecdsa_init(&ctx, curveID, NULL, key_xy);
	res = mbedtls_ecdsa_read_signature(&ctx, hash?shahash:input, hash?sizeof(shahash):length, signature, signaturelen);

	mbedtls_ecdsa_free(&ctx);
	return res;
}


int ecdsa_signature_r_s_verify(mbedtls_ecp_group_id curveID, uint8_t *key_xy, uint8_t *input, int length, uint8_t *r_s, size_t r_s_len, bool hash) {
    int res;
	uint8_t signature[MBEDTLS_ECDSA_MAX_LEN];
	size_t signature_len;

	// convert r & s to ASN.1 signature
    mbedtls_mpi r, s;
    mbedtls_mpi_init(&r);
    mbedtls_mpi_init(&s);
	mbedtls_mpi_read_binary(&r, r_s, r_s_len/2);
	mbedtls_mpi_read_binary(&s, r_s + r_s_len/2, r_s_len/2);
	
	res = ecdsa_signature_to_asn1(&r, &s, signature, &signature_len);
	if (res < 0) {
		return res;
	}
	
	res = ecdsa_signature_verify(curveID, key_xy, input, length, signature, signature_len, hash);

    mbedtls_mpi_free(&r);
    mbedtls_mpi_free(&s);

	return res;
}


#define T_PRIVATE_KEY "C477F9F65C22CCE20657FAA5B2D1D8122336F851A508A1ED04E479C34985BF96"
#define T_Q_X         "B7E08AFDFE94BAD3F1DC8C734798BA1C62B3A0AD1E9EA2A38201CD0889BC7A19"
#define T_Q_Y         "3603F747959DBF7A4BB226E41928729063ADC7AE43529E61B563BBC606CC5E09"
#define T_K           "7A1A7E52797FC8CAAA435D2A4DACE39158504BF204FBE19F14DBB427FAEE50AE"
#define T_R           "2B42F576D07F4165FF65D1F3B1500F81E44C316F1F0B3EF57325B69ACA46104F"
#define T_S           "DC42C2122D6392CD3E3A993A89502A8198C1886FE69D262C4B329BDB6B63FAF1"

int ecdsa_nist_test(bool verbose) {
	int res;
	uint8_t input[] = "Example of ECDSA with P-256";
	mbedtls_ecp_group_id curveID = MBEDTLS_ECP_DP_SECP256R1;
	int length = strlen((char *)input);
	uint8_t signature[300] = {0};
	size_t siglen = 0;

	// NIST ecdsa test
	if (verbose)
		printf("  ECDSA NIST test: ");
	// make signature
	res = ecdsa_signature_create_test(curveID, T_PRIVATE_KEY, T_Q_X, T_Q_Y, T_K, input, length, signature, &siglen);
//	printf("res: %x signature[%x]: %s\n", (res<0)?-res:res, siglen, sprint_hex(signature, siglen));
	if (res)
		goto exit;

	// check vectors
	uint8_t rval[300] = {0};
	uint8_t sval[300] = {0};
	res = ecdsa_asn1_get_signature(signature, siglen, rval, sval);
	if (res)
		goto exit;

	int slen = 0;
	uint8_t rval_s[33] = {0};
	param_gethex_to_eol(T_R, 0, rval_s, sizeof(rval_s), &slen);
	uint8_t sval_s[33] = {0};
	param_gethex_to_eol(T_S, 0, sval_s, sizeof(sval_s), &slen);
	if (strncmp((char *)rval, (char *)rval_s, 32) || strncmp((char *)sval, (char *)sval_s, 32)) {
		printf("R or S check error\n");
		res = 100;
		goto exit;
	}

	// verify signature
	res = ecdsa_signature_verify_keystr(curveID, T_Q_X, T_Q_Y, input, length, signature, siglen, true);
	if (res)
		goto exit;

	// verify wrong signature
	input[0] ^= 0xFF;
	res = ecdsa_signature_verify_keystr(curveID, T_Q_X, T_Q_Y, input, length, signature, siglen, true);
	if (!res) {
		res = 1;
		goto exit;
	}
	if (verbose)
		printf("passed\n");

	// random ecdsa test
	if (verbose)
		printf("  ECDSA binary signature create/check test: ");

	uint8_t key_d[32] = {0};
	uint8_t key_xy[32 * 2 + 2] = {0};
	memset(signature, 0x00, sizeof(signature));
	siglen = 0;

	res = ecdsa_key_create(curveID, key_d, key_xy);
	if (res)
		goto exit;

	res = ecdsa_signature_create(curveID, key_d, key_xy, input, length, signature, &siglen, true);
	if (res)
		goto exit;

	res = ecdsa_signature_verify(curveID, key_xy, input, length, signature, siglen, true);
	if (res)
		goto exit;

	input[0] ^= 0xFF;
	res = ecdsa_signature_verify(curveID, key_xy, input, length, signature, siglen, true);
	if (!res)
		goto exit;

	if (verbose)
		printf("passed\n\n");

	return 0;
exit:
	if (verbose)
		printf("failed\n\n");
	return res;
}
